Automatic weapons, such as machine guns or submachine guns, which are constructed for continuous fire, have a relatively simple trigger mechanism, which is subsequently described in conjunction with FIGS. 8 and 9.
Under the moving range of the breech block (not shown in FIGS. 8 and 9) there is a handle in which a trigger (a) is swivel-mounted. The lateral swivel axis of the trigger is located in the upper midrange of the trigger so that, when the trigger is pulled, the rear upper part of the trigger covers a cam track. The rear upper part of the trigger impacts the front part of a slide stop (f) which, in turn, is swivel-mounted around a lateral axis and attached in the weapon housing or in the handle. The rear part of the slide stop (f) is designed as a sear arm or sear arms. If a spring swivels the trigger (a) forward into neutral position, because of the spring load, the front part of the slide stop (f) swivels downward and the rear part together with the sear arm (s) swivels upward. This position of the sear arm is the arresting position (see FIG. 8). Trigger (a) and slide stop (f) respectively can be absorbed or preloaded by its own or a mutual spring, which pushes them into neutral position (trigger) or arresting position (slide stop).
If now the breech block is pulled back from its frontal neutral position, it moves with its underside the sear arm (s) and, consequently, the rear part of the slide stop (f) downward while moving above the sear arm (s). If a sear catch assembled at the underside of the breech block has moved above the sear arm (s), it snaps upward, being positioned behind the sear catch. The weapon is now loaded and ready to fire.
If the trigger (a) is pulled, the sear arm(s) is lowered until it releases the sear catch; the breech block is released and the weapon starts firing continuously. If the trigger (a) is released, the sear arm moves again springs back into its arresting position, being positioned behind the sear catch and keeping the breech block in a position ready to fire (rear position). Thus, continuous fire is interrupted.
Frequently, the breech mechanism consists of a safety catch that prevents unintentional pulling of the trigger. However, it does not prevent the sear arm from being released as a result of accelerating forces if, for example, the loaded, cocked and safety-engaged machine gun falls from a truck.
Therefore, there are breeches (w) which additionally or alone fix the slide stop (f) in its arresting position at a safety finger. However, this involves the disadvantage that, if the weapon is secured, the breech block cannot be pulled above the arrested slide stop (f), or that it can be jammed on the slide stop (f) because the slide stop cannot give way. FIG. 8 shows a safety barrel (w) which supports by means of its peripheral surface a safety finger (i) of the slide stop (f). A weapon having such a breech (w) cannot be fully loaded while the weapon is in secured position.
Fully automatic weapons operating according to the functional principle described above are increasingly used in so-called weapon stations. In these stations, mounted weapons are aligned by means of a remote controlled actuator and operated by means of actuators impacting the trigger and safety equipment. The actuators may be, for example, electromagnetic. In order to guarantee the highest possible degree of safety, these actuators are designed in such a way that trigger activation is interrupted in case of dysfunctions (for example, power failure) and that, independent of the condition of the weapon, the safety equipment is adjusted to “safe.”
Besides the problem described above of there being no possibility to fully load the secured weapon, another dysfunction can occur in that the weapon continues to fire uncontrollably despite interrupted trigger activation. Extreme operating forces of the actuator can result in the fact that the breech block jams the safety finger (i) in the slide stop (f) to such an extent that the sear arm (s) remains at the breech block without engaging in the sear catch. This dysfunction can occur if the breech block moves forward immediately after trigger activation and power failure results in the fact that simultaneously the trigger is released and the actuator, which impacts the breech block, pushes it into its “safety” position. In this condition of the weapon, the slide stop (f) and sear arm (s) are in release position, and the safety finger (i) connects to the safety recess at the safety equipment (i) (here: safety barrel (w)). If now the actuator moves the safety barrel (w) in the direction of “safe,” the safety finger (i) blocks its adjustment travel and possibly the side of the safety recess pushes so tightly against the safety finger (i) that the slide stop (f) despite being spring-loaded cannot move into its arresting position. The slide stop (f) is jammed above the safety finger (i) and the breech block moves back and forth, firing without interruption, until ammunition supply is interrupted (see FIG. 9).
In view on this problematic situation there are trigger devices in which the sear arm is assembled at a catch jack that is swivel-mounted to a catch lever (see, for example, DE 101 63 003 A1 and US 2004/0194615 A1 or U.S. Pat. No. 6,907,813 B2). In the case of retracting travel of the breech block, said catch jack is swiveled against spring load from its arresting position into standby position in which the breech block can move over the catch jack. In the case of forward travel of the breech block, under the influence of a spring, the sear arm of the catch jack engages in the sear catch and is held in this arresting position by the breech. The catch jack is also equipped with a safety element that interacts with the safety equipment (for example, a safety barrel) in such a way that they can be always returned into their secured position, regardless of the position of the breech or catch lever. At the same time, the safety equipment can impact the trigger as well as the catch lever.
This particular trigger device requires an additional spring element in order to secure the catch function, and the catch jack and its swivel attachment must carry the full force of the forward traveling breech. In the process, the comparatively small catch jack and its attachment are placed under extreme dynamic stress. In worst case scenario, a possible crack or malfunction of the catch jack, its attachment in the catch lever and/or spring element have such an effect on the function of the weapon that the weapon, independent of the position of the safety device and trigger, continues to fire until the entire supply of ammunition has been fired. Moreover, the operating force of the spring element has to be precisely adjusted to the spring-load impacting the catch lever. Otherwise, the breech block moving over the catch jack also pushes the catch lever downward into the handle. This can possibly seriously affect the interaction between the safety element and safety barrel.